Process of rendering



July 10, 1934. T, K. LOWRY PROCESS OF RENDERING 2 Sheets-Sheet 1 FiledMarch 17, 1950 a r i n Ava/WU \W\\\ m 0 W J 4 1 5 z I 1 1 5 m 4 z O 5 2a H/ Z ./1 1 W Mr, G 5 1 ,U/

July 10, 1934. T. K. LOWRY PROCESS OF RENDERING Filed March 17, 1930 2Sheets-Sheet 2 Patented July 10, 193

PROCESS OF RENDERING Thomas K. Lowry, Chicago, 111., assignor to Darling& Company, a corporation of Illinois Application March 17, 1930, SerialNo. 436,401 23 Claims. (01. 87l3) oi the smaller streams after which thesmaller This invention relates particularly to the rendering ofmaterials such as meats, fats, garbage,

bones and the like, and has jects moisture therein and to sepa for oneof its obthe cooking of the material to drive oil the rate thesubstances forming the material, from each other.

Another object of this invention is to provide a heating unit whichemploys a maximum amount or" heating surface, thereby making it possibleto use a heating medium at a lower temperature than isnecessary withapparatus now in use.

Another object of this invention is to provide means for circulating thematerial being rendered through a heating unit and for passing theheated material into a separator wherein the vapors are drawn off theheated substance.

resides in the heating surface so that a rapid transfer of heat resultsas the material flows thereover.

Another object of this invention is to provide a continuous circuit forthe material ,to be rendered which will enable the same to be passedsue-- cessively through the heating unit and the separator as many timesas desire Another object of this invention is to provide a heating unithaving longitudinal passages therein for the material being rendered,the passages being sufliciently large to permit the passage therethroughof the material without any serious clogging effect on the passages.Means is provided for permitting ready ac cess to the passages to cleanthe same if they should become clogged.

Another object of this invention resides in dismaller massesindividually to be rendered into a plurality and subjecting each ofthese I the action of heat.

Another object of this invention resides in flowing the entire mass tobe rendered and dividing,the same into small streams each of which iss'urroundedby a heating me dium.

Another object of this invention resides in flowing the entire mass tobe re ndered in a parent stream, dividing said parent stream intosmaller streams all flowing substantially in the same direction, heatingthe smaller streams by a heating means surrounding each stream, andagain reuniting the smaller streams aiter they have been heated.

Another object of this invention resides in the to be rendered in aclosed path, and subdividing the stream of material being circulatedinto smaller streams at a point in of said material to be rendere thepath of travel d, and heating each streams reunite and are carried alongtheir path of movement to a chamber in which the moisture liberatedduring the heating by means of a vacuum, or

Another object of this inventi agitating of the mass over operation isremoved in any other desired 6 manner, the residue continuing itsmovement along said closed path to the point wherein the material isagain subdivided into smaller streams and heated while in that state.

the entrance ends of the various tubes.

A still further object of provide means for mixing or other rendered fatwith this invention is to a quantity of tallow the meat to be renderedbefore the meat is heated to extract the tallow therefrom. Meat is toflow through the system by itself ordinarily, and therefore I prefer touse the tallow to act as a vehicle to carry the meat through therendering apparatus.

Furthermore, by providing the tallow, scorching of the meat is'preventedand a more uniform cooking of the meat results. ed in a jacketed mixerso tallow and meat will more the system. crate by means of gravity Thetallow and meat are preferably heatthat the mixture of readily flowthrough It is possible to have the system opby making the mixturesufiiciently fluid although I prefer to. use some form of circulatingmeans to circulate the material through the system. When renderingcertain substances containing a high percentage of grease or fat it iscle such as tallow, substance being rendered since these substances area slight heating to carry entire process of rendering.

unnecessary to use any vehiiard or grease to carry the through thesystem sufficiently fluid after the same through the Other objects ofthis invention will be apparent as the description of the embodimentsshown in the drawings proceeds.

In the drawings- Fig. 1 shows more or less diagrammatically anembodiment of my invention as applied tothe rendering of meats;

Fig. 2 is a cross-section 2-2 0! Fig. l; and

taken along the line on resides in the 6 Fig. 3 shows a modifiedarrangement of the rendering apparatus.

I shall proceed to describe my process as applied to the rendering ofmeats but I wish to have it understood that the same system may be usedin rendering other substances such as those previously mentioned.

At the present time there are three different types of rendering systemsused for the rendering of meats and the like. The oldest of thesesystems is known as the open kettle system in which the substance to berendered is heated in an open kettle to drive off the moisture. This isnot very satisfactory but is still used to some extent. Next inimportance is the wet rendering system. This requires the use of avertical pressure tank in which the material is placed, and live steamat a pressure of approximately forty pounds per square inch is turneddirectly into the material which is in the tank. The mixture is cookedfor a period of approximately eight or ten hours duringwhich time thereis a considerable condensation of steam so that when the material iscooked the tank contains considerable water in addition to the solidsubstances and the tallow. After the steam is turned off the tallowrises to the top and is drained off as is most of the water and thewater and solid substances which are left in the tank are dropped intowhat is known as a slush box. From this point, the water, which is knownas tank water, is drained off and this water is evaporated. Theconcentrated liquors from the evaporator resulting after the evaporationand draining off of the water is known to the trade as stick". Thisstick has to be further dried in order to be usable. The solid substanceknown as tankage is pressed in hydraulic presses in order to eliminateas much moisture and grease therefrom as possible and thereafter thesame is dried.

The other system known as the "dry rendering system which is the mostrecent development, is supposed to be an improvement on the wetrendering system inasmuch as the heating of the steam is transmitted tothe meat through a jacketed tank, and the steam does not itself comeinto direct contact with the meat. The tanks which contain the meat tobe treated must be provided with means for agitating the meat while itis being heated in order to bring the meat into contact with the heatingsurface and to prevent scorching. When the material is cooked in thismanneryonly two products result, tallow and the residue which is knownas cracklings". This process eliminates tank water and the necessaryoperations in evaporating and drying the material after it is cooked.This process, while saving some in steam, necessarily consumes aconsiderable amount of power which is required in order to stir thematerial while in the tank. In dry rendering systems it is customary tohash or grind the material to a comparatively uniform size beforecooking the same.

A disadvantage of the dry rendering processes which are now known isthat the amount of heating surface is small as this heating surfaceusually comprises only a steam jacket. In order to compensate for therelatively small amount of heating surface, it is necessary to use steamunder high pressure (sometimes as high as 50#). If lower pressures orcorresponding lower temperatures were used it would cut down thecapacity of the machine and lengthen the time of cooking, whereas withthe high pressure steam which is necessary in order to get the desiredcapacity, a portion of the material generally scorches and causes adiscoloration of the tallow. By the use of low pressure steam andcooking the material over a longer period of time there would not be asmuch scorching but the length of time that the material would take tocook would result in a discoloration of the tallow. In other words, ifhigh pressure steam is used, the material scorches due to the fact thatthe temperatures are too high for proper cooking of the material withoutscorching and if low pressure steam or low temperatures are used, theprocess requires such a long period of time as to result in thediscoloration of the tallow due to the slow cooking of the material. Ifsufl'lcient heating surface is provided the material will cook in a muchshorter time.

The most important factor in the dry rendering process is the questionof heating surface, and in the apparatus which I have disclosed, I showmeans whereby a great amount of heating surface is obtained Within alimited space, and'in which the moisture is driven off in a chamberwhich is separate from the space in which the material is heated. Notonly that, but I have provided means for circulating the materialthrough the system as many timesas desired, the material being removedfrom the system as soon as the mixture has been properly cooked and themoisture driven therefrom. Another advantage resulting from the use ofmy process is that I can obtain a rapid circulation of the material overthe heating surface so that I obtain a rapid transfer of heat from theheating surface to the substance. Also if necessary I may provide meansfor recirculating the material through the system as many times asnecessary.

In the present process, the material or mass to be rendered, which maycomprise such materials as meat, garbage, animal matter, fish, etc., iscirculated in a parent stream along a predetermined path to a heatingunit at which point in the path of movement thereof, the parent streamis subdivided into a plurality of smaller streams which are eachsurrounded by a heating medium which is preferably out of direct contactwith the material in the streams. After the heating of the material isaccomplished, the streams are thereafter reunited into a single flowingstream forming the parent stream, flowing to a separator 29 where thematerial is subjected to a high degree of vacuum for the purpose ofdrawing off the vapors which were liberated from the material during theheating of the streams. The material thereafter continues its path ofmovement as a single stream through suitable conduits back to the pointin the path where the parent stream is subdivided into the smallerstreams, the process being continued until substantially all of themoisture has been removed from the material and the tallow freed fromthe residue although still associated therewith in the mixture. At thepoint where the material is subdivided into the smaller streams, thematerial is agitated so that the means which divides the parent streaminto a plurality of streams is not clogged by the accumulation of largeparticles of the material to be rendered or by bones, etc., straddlingthe dividing means which in this case consists of a perforated platehaving a plurality of openings communicating with the passages throughwhich the streams flow after divided from the parent stream. Thisagitation is accomplished in the present instance by the substance beingflowed in wearer the proper direction to agitate the material adjacentthe dividing means as will appear hereinafter.

Referring more particularly now to the draw ings, the numeral 1represents a mixing tank having a steam jacket 2 surrounding a portionthereor. The steam jacket 2 is provided with an inlet a and an outlet 3.A rotatable shaft 5 is journaled in suitable bearings in the brackets 6and 7 secured to the sides of the mixing tank 1. A pulley 8 on the upperend thereof may be connected by means of a suitable belt to a source ofpower so that the shaft 5 may be rotated when desired. However, thisshaft may be rotated in any other suitable manner, and I do not wish tolimit myself to a pulley and a belt drive therefor.

The rotatable shaft 5 carries mixing paddles 9. A quantity or materialis placed within the mixing tank 1 along with a quantity of tallow, andas the shaft 5 is rotated paddles 9 stir the tallow and material tothoroughly mix the same. The mixture is then heated slightly by means ofthe steam in the jacket 2 and the tallow acts as a vehicle for carryingthe material through the system and for transferring the heat from theheating surfaces to the material itself. I prefer to use about equalquantities by weight of the material and tallow, but it will beunderstood, of course, that the proportion of meat and tallow may bevaried in order to make the mixture or" the proper consistency. Afterthe meat and tallow have been thoroughly mixed, the valve 10, which upuntil this time has been closed, is opened to permit the mixture todrain out of the hopper by gravity through the pipe 11 and downwardlytowards the pump 12. The pump 12 is of the centrifugal type and iscapable of handling large pieces of solid material as well as liquids.Such pumps are of a well known variety and are commonly used for pumpingsewage and the like. The pump 12 forces the material through theconduits 13, 1a and 15 through the valve 16 which is open at this timeand into the heating unit designated generally as 17. The heating unitcomprises an outer shell 18 which is cylindrical in cross-section andheads 19 and 20 are fitted over the end or the shell 18. A plate such as21 is made integral with the end of the shell 18 at each end thereof, orif desired, this platemay be made separate from the shell. Tubularmembers '22 have their open ends fitted within suitable openings in theplates 21 and form passages communicating with the interiors of theheads 19 and 20. A second plate at the other end of the shell andsimilar to the plate 21 receives the other ends or the pipes.

Steam is introduced into the heating unit 1'7 between the plates 21 andaround the tubular members 22 by means of an inlet conduit 24. Thecondensation escapes through an outlet 23., The material is forcedthrough the tubular members 22, which are or" 'sufiicient diameter topermit the solid substances to pass therethrough without clogging thetubular members. Due to the ar rangement or" the tubes within theheating unit 17, 1 may secure a maximum amount of heating surface forthe heating unit. In other words, practically all the steam which passesthrough the heating unit comes into intimate association with the outersurfaces or" the tubular members and due to the fact that the tallowwhich is mixed with the meat comes into intimate association with theinterior surfaces of said tubular members and conveys the heat from thetubular members to the meat, 2. very rapid transfer of heat between thesteam and the meat is accomplished. As stated before, the material isintroduced through the conduit 15 and valve 16 into the heating unit 17.A short section of pipe 25 connects the valve 16 with the head 19 and isso arranged that the material enters the head 19 at a tangent causingthe mixture to be thoroughly circulated within the head 19 transverselyof the longitudinal dimensions of the pipes and causing the mixture tobe evenly distributed to all of the tubular members 22 and preventingthe clogging of the pipes by bones or large pieces of meat which mightotherwise come to rest straddling the open ends of the tubes and remainthere thus preventing other material from passing into the pipes. Thepressure exerted on the mixture by means of the pump 12 forces themixture through the tubular members 22 downwardly into the lower head20, and the mixture escapes through the bottom of this head through theconduits 26 and 28 to the separator 29.

The separator 29 is in the form of a hollow chamber and contains thebattles 30 arranged in the manner illustrated. The pipe 31 communicatingwith the upper end of the separator is adapted to be connected with anysuitable source of vacuum or may be in communication with a suitablecondenser of any well known construction. The purpose of the separatoris to remove the vapors from the mixture. As the material passes throughthe heating unit 1'7, the mixture of course is heated or cooked, andthis rise in tem- 'perature liberates a certain amount of moisture whenthe mixture reaches the separator 29 due to the fact that the degree orpressure within the separator causes the moisture to change into a vaporand be carried an through the conduit 31. The bailies 30 are for thepurpose of preventing entrained particles from being drawn out of theseparator through the conduit 31.

By the time the mixture which is drawn from the mixer 1 has beencirculated as far as the separator, practically all of the mixture hasbeen drawn out of the mixer, and, as soon as this is done, the valve 10is closed so as to cut out the mixing tank during the cooking operation.The mixture within the separator 29 communicates by means of a valve 32and conduit 33 with the pump 12, and with the valve 32 open the pumpcrculates and re-circulates the substance through the conduits 13, 1 and15, valve 16, conduit 25, heating unit 1'7, conduits 26 and 28,separator 29, valve 32 and pipe 33, and forms a closed circuit throughwhich the substance is or may be repeatedly circulated. Generallyspeaking, a single circulation of the mixture through the circuit justdescribed is not sufliicient to drive all of the moisture out of themixture and therefore it becomes necessary to circulate the mixturethrough the circuit several times.

The material asit enters the separator begins to froth and tends to risein the separator and the amount of froth may be determined by lookingthrough the transparent openings 34 in the wall of the separator. apredetermined degree the operator may determine when the rendering hasbeen carried on a sufiicient length of time.

Between the conduits 13 and 14 I arrange a T '35 which communicates witha valve 36. Similarly I arrange a T 37 between the conduits 26 and 'i'38 which latter has one branch thereof communicating with the conduit28, and another communicating with the T 37. The T 37 also communicateswith a valve 39. The cross 41 When the frothing lessens to communicateswith the pump 12, conduit 11 and conduit 33. The remaining connection ofthe cross communicates with the T 38 by means of a valve 42. A T 43 isarranged between the conduit 15 and valve 16 and one. branch thereofcommunicates with the conduit 44 by way of the valve 45.

During the normal circulation of the mixture through the circuit, thevalves 36, 39, 42 and 45 remain closed, whereas the valves 32 and 16remain open, it being understood of course, that the valve 10 is alsoclosed immediatelyafter the mixture has all been introduced into thecirculating system.

After the material has been circulated the desired number of times andthe moisture driven therefrom it is necessary to remove the residue fromthe system and I may do this in either of two ways. I may open thevalves 39 and 36 and permit the material to drain out of the system andin order to break the vacuum within the separator 29 and heating unit17, I provide pet cocks 46 and 47 communicating with the atmosphere andwith the interiors of the separator 29 and heating unit 1'7respectively. By this method I am enabled to drain most of the residueout of the system by gravity but generally a small quantity of theresidue remains in the system. However, no harm is done by permitting asmall amount of the residue to remain in the system as this can becarriedalong with the next quantity of the mixture which is cooked.

The method which I have just described for removing the residue from thesystem is fairly satisfactory for ordinary purposes, and if it isdesired merely to drain the residue into suitable hoppers or receptaclesin which the same are transferred to suitable apparatus for extractingthe tallow from the meat. Such apparatus may be of any of the well knowntypes, and forms no part of the present invention. In practice however,I find it advisable to convey the residue to a point above the apparatusas installed or to the top of the apparatus which separates the tallowfrom the residue. For this purpose I provide the valves 45 and 42 anduse the pump 12 which circulates the mixture during the normal operationof the machine to force the material out through the valve 45 andconduit 44 to the desired place.

When ejecting the residue by means of the pump 12 I leave the valves 39and 36 closed and close valve 16. I also open valves 42 and 45 andpermit the valve 32 to remain open. -Pet cocks 46 and 47 are also openedso that the interior of the heating unit 1'7 and the separator 29communicate with the atmosphere. As the pump 12 is operated the residueis drawn from the heating unit 17 and separator 29 and is forced throughthe conduits 13, 14 and 15, T 43, valve 45 and conduit 44 to any desiredposition. In this manner practically the entire system is cleaned outand the apparatus is now ready for the cooking of a new batch of themixture of meat and tallow. This new batch may be mixed while thecooking of the previous batch is taking place, so that as soon as theresidue is driven out of the system the valve 10 may be opened to permitthe mixture to be drawn into the system for circulation, therebyreducing the amount of time necessary for the carrying out of theprocess'.

I will now proceed to enumerate some of the advantages of my improvedsystem over the prior art constructions. With a system arrangedaccording to my invention, a great amount of heating surface within theheating unit 17 is utilized in view of the fact that no agitating meansis necessary within the heating unit. Furthermore, the arrangement ofthe heating unit is such that none of the mixture is ever a very greatdistance away from a heating surface, and therefore more or less is in aposition to receive by a very short route the heat which is transferredfrom the heating surface to the mixture. This results in heating thesubstance more quickly due to the fact that every particle of themixture is receiving heat from the heating surface practically at alltimes and in considerable quantities, whereas in the previous rotatingdrum type, the material only came' into contact with the heating surfaceoccasionally, and therefore it was necessary to maintain the heatingsurface at a higher temperature in order to compensate for the smallamount of time which the material was in contact with, or in closeproximity to the heating surface. The system which I have described,furthermore has the advantage of speeding up the time required for thecomplete cooking of a given quantity of meat. This is made possible bythe fact that the pump circulates the meat and tallow through thepassages 22 very rapidly and this causes a very quick transfer of heatfrom the heating surface to the tallow and the moat. Furthermore, eachtime the material passes through the heater, there is less moisture inthe mixture and consequently that moisture which remains is much morereadily heated and driven off therefrom.

The arrangement of the conduit 25 is such as to provide a rather uniformdistribution of the meat to the various tubular members 22, and insuresthat the material will be forced through all of the tubular members atsubstantially the same rate.

Another advantage of this system is that the tallow which is used inconjunction with the material being rendered to flow the materialthrough the system also acts as a heat exchanging medium whichdistributes the heat from the heating surfaces of the tubes and causes amore even distribution of the heat to the material being renderedwhereby there is less tendency for the material to be scorched. Bypreventing the scorching of the material, the general appearance of thetallow is improved and is rendered more saleable. The tallow produced inthis manner is also of a higher quality than the tallow which has beenscorched even slightly during the cooking operation.

With devices of the prior art if a hightemperature were not used for theheating surfaces,

it would be necessary to continue the process for 1 a considerableperiod of time, and thus cause a discoloration of the tallow due to thelength of time necessary for the cooking process. With a system such asI have illustrated however, the cooking process is speeded up due to thefact that I have provided a greater amount of heating surface perquantity of material cooked than has a suitable vacuum source which maybe a vacuum pump-and a condensersuch as a surface condenser or a jetcondenser in case a high vacuum is necessary or it may be a condenser ofany other type. Such condensers are common in the art to which thisinvention pertains and to the related arts, and no description thereofis deemed to be necessary for the complete understanding of the processand apparatus which I have described.

In Fig. 3 I have illustrated a modified apparatus for carrying out myprocess. In this form of the invention the steam jacketed mixer 50similar to the mixer 1, as shown in Fig. 1, has a rotatable shaft 51 andmixing paddles 52, the mixer being surrounded by a steam jacket 53. Inthis form of the invention I have illustrated the conduit 54 ascommunicating with the interior of the mixer at a point above the bottomof the mixer. This is for the purpose of permitting any foreign solidparticles such as crockery, pieces of metal, and the like' which areoften found in the raw material to gravitate to the bottom of the mixerand the same may then be drawn out of the mixer at any desired timethrough the valve 55 and conduit 56'. It will be seen by thisarrangement that the heavy foreign solid substances are not apt totravel downwardly through conduit 54 to the pump 55 which corresponds tothe pump 12 in Fig. 1. While these solid substances will pass throughthe pump 55 without clogging, still the same substances may clog otherparts of the apparatus and it is desired to rid the material beingrendered of any foreign solid substances before the same is carried intothe heating unit. The mixer 50 therefore acts as a separator orclassifier. It will be understood also that this form of mixer may beused with the apparatus illustrated in Fig. 1 in place of the mixershown in that apparatus.

The material drawn from the mixer 50 passes through the valve 57 anddownwardly through the conduit 56 into the pump 55. The pump pumps thematerial through the conduit 58, conduit 60 and valve 61 into the upperpart of the casing indicated generally as 62. The upper part of thiscasing 62 forms a separator 63 and the lower part forms a heating unit64. These parts correspond to the separator 29 and heating unit 1'7illustrated in Fig. 1 and perform the same function although in perhapsa slightly different manner.

The heating unit 64 is provided with tubular members 65 extendinglongitudinally thereof, the

upper ends of these tubes communicating with the interior of theseparator 63 and the lower ends thereof communicating with the head 66at the lower end of the heating unit. Steam is admitted into the spacesurrounding the tubes 65 through the conduit 67 and the condensation isdrawn through the conduit 68. The material being rendered' passesdownwardly through the tubes 65 and into the head 66. The pump 55 drawsthe material downwardly from the head 66 through the valve 69 andconduit 56 and then recirculates the material through the conduit 58,conduit 60 and valve 61 to the separator 63.

A partial vacuum is maintained within the separator 63 by means ofasuitable vacuum producing unit communicating with the interior of theseparator by means of the conduit 70. Baflles '71 and transparentopenings 72 similar to the bailies 30 and transparent openings 34 shownin Fig. 1 are, provided for the separator 63 and perform the samefunctions as these parts 30 and 34.

After the material has been heated by means of the heating unit 64 andcirculated by means of the pump back'into the separator 63, the vaporescapes from the heated mixture and passes out through the conduit 70,the baffles 71 acting to separate the entrained particles from thevapor. The mixture is again passed downwardly through the tubes 65, isagain heated and forced back into the separator by means of the pump 55where again some of the moisture is driven off through the conduit 70.This process is continued until the operator determines that the mixturehas been cooked a sufiicient length of time.

After the mixture has been cooked a suflicient length of time, theoperator desires to remove the material from the system, and in order todo this he closes the valve 61 and opens the valve 73 which communicateswith the conduit 60. The pump 55 is thereafter used to pump the materialthrough the conduit 60, valve 73 and conduit 74 to any desired place. Itwill be understood, of course, that the valve 57 is closed after themixture has been drawn out of the mixer 50 and remains closed until itis desired to place a new quantity into circulation.

If desired, the material may be drained out of the system by gravity.Thisis accomplished by opening the valve 59 instead of the valve 73 andpermitting the material to flow by gravity out of the heating unit'64and the separator 63 in a manner similar to the way in which thematerial is drained out of the separator 29 and heating unit 1'7 shownin Fig. 1 through the valves 39 and 36. The pet cock 75 is used to breakthe vacuum with in the separator to permit the material to be expelledby the pump or drawn off by gravity through the valve 59.

The operation of this form of the apparatus will be well understoodafter reading the description of Figs. 1 and 2, and therefore it isbelieved that no further description as to the operation of thisapparatus is necessary.

With a system such as I have described, it is desirable, although notalways necessary to hash or crush the raw material so that I may usecomparatively small sized heating tubes. While I have shown straighttubes for conveying the material through the heating unit it will beunderstood of course, that these are merely illustrative of the type oftubes which I may use and if desired these tubes may be coiled insteadof straight or the heating unit may be of a type different from theexact type of heating unit-which I have illustrated in the drawings. Theimportant feature of my invention is that the material is fiowed rapidlyover the heating surfaces and then recirculated if necessary to producea rapid transfer of heat from the heating surface to the material.

If desired, the material may flow from. the bottom of the heating tankto the top instead of from the top to the bottom as illustrated withoutdeparting from the spirit of this invention.

If the material itself is sufficiently fiuid to permit it to flowthrough the system during the entire process no tallow or like substanceis added. Some substances such as pork, beef, fat and the like becomesufliciently fluid in the mixer due to the high grease content to'fiowthrough the system without adding othersubstances thereto to act as avehicle. When rendering garbage a quantity of garbage grease is usedsince although garbage is sufficiently fluid at first (generallyspeaking) the same becomes less fluid as, the moisture is driven out ofthe same and ifeadditional grease were not used it would be verydifficult to cause the garbage to flow through the system near the endof the rendering operation.

If desired, vegetable oils may be usedas the vehicle for conveying thesubstance instead of fats. This is particularly desirable in producingcompound lards. Cotton seed oil, which is often used in producingcompound lards has to be deodorized before it will be found desirablefor use in the compound lard. This deodorizing is ordinarilyaccomplished by placing the oil in a vacuum chamber and passing steaminto the oilthe steam removing the foreign matter which gives the odorto the oil. If cotton seed oil were used in my "circulating renderingsystem, the heated vapor released from the substance being renderedwould have the same effect on the oil as the steam does ordinarily andthe separator being under vacuum would remove the vapors along with theforeign, odor producing matter, thus simultaneously liberating theundesirable matter from the oil and rendering the fat to produce acompound lard.

This invention also can be used in the rendering of flsh and sea animalsand has found its application particularly in the rendering of whales inthe whaling industry.

I do not wish to limit myself to the particular details of the apparatuswhich I have'described as it is within the scope of one skilled in theart to which this invention pertains to change the position of thevarious units without departing from the spirit of this invention. Theaccompanying drawings are to be taken merely as illustrative of oneembodiment of my invention and not as defining the limits thereof as Ido not wish to be limited in my invention except as pointed out in theaccompanying claims.

Having thus fully described my invention, what I desire to secure byLetters Patent of the United States is:

1. A process of rendering meats, garbage, and the like, comprising thesteps of flowing the substance to be rendered simultaneously through amultiplicity of stationary heated passages arranged close together,maintaining said passages substantially filled with the substance to berendered at all times, removing the volatile matter from said cookedmaterial, passing said heated material through stationary heatedpassages after some of said moisture has been removed therefrom with asubsequent step of removing additional moisture from the heated materialafter said last mentioned step of passing the material through heatedpassages.

2. The process of rendering a substance containing material renderedfluid upon the application of heat thereto, which fluid acts as the onlyvehicle for carrying the substance to be rendered, flowing the substancealong a predetermined path in a parent stream, subdividing the parentstream into similarly moving individual streams and flowing said streamssimultaneously through separate narrow heated passages unobstructed byany mechanical means for flowing the substance therethrough with a.fluid resulting from the rendering of that material, removing moisturefrom said material after it has been heated, and subsequently positivelycirculating the material being rendered through narrow heated passagesand removing additional quantities of moisture therefrom while thematerial is carried by said fluid and until substantially only 5%moisture remains in the material being rendered.

3. A rendering process comprising the steps of flowing a quantity of thesubstance to be rendered simultaneously through a plurality of narrowheated stationary passages, the walls of which are not spacedsubstantially over six inches from each other, and drawing off the vaporliberated from the material being rendered during the flowing of thesolid material through said passages, and collecting all of the materialflowing through said passages and flowing all of the same through acommon passage.

4. A process of rendering comprising the steps of flowing material to berendered simultaneously through a plurality of stationary narrowsubstantially heated passages with the material being rendered conveyedthrough said passages solely by a fluid of the same character as thatproduced by heating the material, and removing the moisture from saidmaterial liberated by said heating process until only a small percentageof the moisture remains in said material.

5. A process of rendering comprising the steps of flowing material to berendered simultaneously through a plurality of narrow stationarysubstantially unobstructed heated passages while cenveyed by a fluidwhich evaporates at a higher temperature than that used in the renderingprocess under the conditions in which the said material is rendered,heating the material to be rendered to a temperature to liberate themoisture therefrom, and removing the moisture from said material afterit is liberated until only a small percentage of moisture remains insaid material.

6. A process of rendering comprising the steps of mixing a quantity ofsolid material to be rendered with a quantity of fat, flowing parts ofthe mixture substantially simultaneously through a plurality ofstationary unobstructed narrow heated passages, and continuouslyremoving the moisture from said mixture as the same is liberated.

'I. A process of rendering comprising the steps of mixing a quantity ofsolid material to be rendered with a quantity of fat, flowing parts ofthe mixture substantially simultaneously through a plurality ofstationary unobstructed narrow heated passages, and continuouslyremoving the moisture from said mixture under vacuum as the same isliberated.

8. A process of rendering comprising the steps of mixing a quantity ofsolid material to be rendered with a quantity of fat, flowing parts ofthe mixture substantially simultaneously through a plurality ofstationary unobstructed narrow heated passages, continuously removingthe moisture from said mixture as the same is liberated, and repeatingeach of the steps of flowing the mixture through stationary unobstructednarrow heated passages and removing the moisture as many times asnecessary to remove the desired amount of moisture therefrom.

9. A process of rendering comprising the steps of flowing a substancethrough a plurality of stationary narrow heated passages, feeding saidplurality of stationary heated passages simultaneously through a commonsupply passage and agitating the material to be rendered adjacent theends of the passages to which the material is supplied to prevent theclogging of the material adjacent the ends of said passages.

10. A process of rendering comprising the steps of flowing a substancethrough a plurality of stationary narrow heated passages, feeding saidplurality of stationary heated passages simultaneously through a commonsupply passage and agitating the material to be rendered adjacent theends of the passages to which the material is supplied by directing thematerial to be rendered through said common supply passage in adirection to cause a complete circulation of the material adjacent theends of said passages as said material is supplied to the ends of saidpassages through said common supply passage to prevent the clogging ofthe material adjacent the ends of said passages.

11. The process of rendering which includes the steps of comminuting themass to be rendered, then subdividing the mass into smaller masses andcausing them to flow in separate individual streams, and surroundingsaid streams with, and subjecting them to, the action of heat.

12. The process of rendering meat,garbage,and the like consisting of thesteps of causing the mass to flow in a continuous circuit, a part ofsaid circuit branching into a plurality of small streams flowing insubstantially parallel relation with each other, subsequently collectingsaid streams into the single stream of the main circuit, subjecting saidsmaller streams to heat by entirely surrounding each of them with astationary heating element carrying a heating medium, and separatingsaid streams from the heating medium to prevent direct contacttherewith.

13. The process of rendering meat, garbage, and the like which includesflowing the mass to be rendered in a parent stream, subdividing theparent stream into a plurality of downwardflowing smaller streams,imparting to the main stream at the point where it subdivides into thesmaller streams, a rotary motion substantially in a plane perpendicularto the smaller streams to thereby agitate the mass and to distribute thelarger particles of solid matter to prevent clog ging of the smallerstreams, and individually and simultaneously heating said smallerstreams.

14. The process of' rendering meat, garbage, and the like, whichincludes the steps of flowing the mass to be rendered in a parentstream, subdividing the parent stream into a plurality of downwardflowing small streams, imparting a rotary motion substantially in ahorizontal plane to the main stream at the point where it subdividesinto the small streams to thereby agitate the mass and distribute thelarger particles of solid matter to prevent clogging of the smallstreams, and individually and simultaneously heating said small streams.

15. The process of rendering which includes the steps of positivelycirculating the mass to be rendered in a single parent stream, thensubdividing the mass into smaller masses and causing them to flow inindividual similarly moving finer streams, and surrounding said streamswith and subjecting them to the action of heat.

16. The process of rendering which includes the steps of positivelycirculating the mass to be rendered in a single stream, thensub-dividing the mass into smaller masses and causing them to flow inindividual similarly moving finer streams, subjecting said streams fromall sides to the action of a heating medium, and separating said streamsfrom said heating medium to avoid direct contact therewith.

17. The process of rendering a mass composed of a mixture of a quantityof solid material to be rendered and a quantity of fat, which comprisesthe steps of sub-dividing the mass into smaller masses and causing themto flow in individual streams, and surrounding said streams withstationary heating elements and subjecting the streams to the action ofthe heat of the elements.

18. A process of rendering comprising the steps of mixing a quantity ofsolid material to be rendered with a quantity of fat, dividing themixture into smaller masses and flowing the same simultaneously througha multiplicity of stationary narrow heated passages, removing thevolatile matter from said mixture as the same is liberated therefrom,thereafter again passing the solid material and fat through said narrowheated passages and again removing the moisture liberated therefrom, andrepeating these steps as many times as necessary to drive off thenecessary amount of moisture from the material, without separating theheated fat and fluid products of rendering from the material, wherebysaid heated fat and fluid products of rendering will act as a vehicle tocarry the material through the various steps of the process while themoisture is being liberated and withdrawn from the mixture.

19. The process of rendering comprising the steps of heating the solidmaterial to be rendered to a temperature sufficient to release a portionof the fluid contained therein whereby said fluid acts as a vehicle tocarry said material through the various stages of rendering, flowingsaid material and fluid simultaneously in a common stream, dividing saidstream into a plurality of similarly moving finer individual streams,surrounding said streams with and subjecting them to the action of heat,thereafter again passing the said material while carried by said fluidback to the original common stream, removing the moisture liberatedtherefrom, and again dividing said stream into a plurality of finerindividual similarly moving streams, and repeating these steps asoutlined as many times as is necessary to drive off the desired amountof moisture.

20. The process of rendering meat and the like comprising the steps ofpumping the material to be rendered in a parent stream, dividing theparent stream into a plurality of similarly moving finer streams, andsurrounding said finer streams with and subjecting them to the action ofheat.

21. The process of dry rendering fat and moisture-bearing materials suchas meats, garbage and the like which consists in the steps of rapidlyand positively circulating the material through an externally heatedzone, being of a cross-section large enough to permit movement of saidmaterial through said zone without clogging and being small enough incross-section to permit a rapid transfer of externally applied heatthrough zone and the withdrawal of steam'until said material iscompletely rendered.

22. The process of dry rendering fat and moisture-bearing materials suchas meats, garbage and the like, which consists in the steps of rapidlyand positively circulating the material through a plurality ofexternally heated passages, each of said passages being of across-section large enough to permit movement of said materialtherethrough without clogging and being small enough in cross-section topermit a rapid transfer of externally applied heat through saidmaterial, maintaining the temperature of the material included withinsaid passages, through the agency of said externally applied heat, at apoint suiricient to melt the fat and convert the moisture into steam,drawing off the steam during the circulating operation, and repeatingthe circulation of the material through said passages and the withdrawalof moisture until said material is completely rendered.

23. The process of dry rendering fat and moisture-bearing materials suchas meats, garbage and the like which consists in the steps of rapidlyand positively circulating the material through an externally heatedzone, being of a cross-section large enough to permit movement of saidmaterial through said zone without clogging and being small enough incross-section to permit a eaaler

